Question

Intermediate lobe of pituitary secretes a hormone known as _____.
a. Oxytocin
b. Melanocyte-stimulating hormone
c. Corticotropin releasing hormone
d. Thyrotropin releasing hormone

Answer 1

Hint: Pituitary gland is a part of the endocrine system. It serves many purposes; however, its main function is to secrete hormones into the bloodstream that affects other glands and organs. This gland is located in the sella turcica (Turkish saddle) which is a bony, hollow space at the base of the skull, behind the bridge of our nose and underneath the brain.

Complete answer:
A few points on the structure of pituitary gland:
The pituitary gland is a pea-sized gland that is attached to the hypothalamus by a stalk-like structure.
It has two lobes: the anterior and posterior lobes. The two lobes are joined by the intermediate lobe.

• Anterior lobe: This lobe of the pituitary synthesizes and secretes hormones.
• Intermediate lobe: This lobe synthesizes and secretes melanocyte-stimulating hormone (MSH) which causes the release of melanin pigment in skin melanocytes, or pigment cells. This hormone is also synthesized in the anterior lobe, but when produced by an intermediate lobe, it is also known as “intermedins”.
• Posterior lobe: This part of the pituitary gland stores and secretes endocrine hormones like antidiuretic hormone (ADH) and oxytocin. However, it does not synthesize these hormones.

Thus, Intermediate lobe of the pituitary secretes a hormone known as Melanocyte - stimulating hormone.

As can be seen from the above points, intermediate lobe of the pituitary gland secretes melanocyte -stimulating hormone, or MSH, while oxytocin is secreted by the posterior lobe and corticotropin releasing hormone and thyrotropin releasing hormones are secreted by the anterior lobe.

Hence, the correct answer is option (B).

Additional information:
The many hormones secreted from pituitary gland help in controlling the following processes-
• Growth
• Breast milk production
• Blood pressure regulation
• Water and osmolarity regulation in the body
• Temperature regulation
• Water balance by control of reabsorption of water by the kidneys
• Conversion of food into energy
• Sex organ functions (in both sexes)
• Uterine contractions during childbirth and some other aspects of pregnancy
• Pain relief
• Function of the thyroid gland.

Note: Pituitary gland is also known as the master gland since it is a part of several processes. The intermediate lobe is either very small or completely absent in adult human beings. In lower vertebrates, like fish and amphibians, MSH ( melanocyte-stimulating hormone) from the intermediate lobe causes skin darkening, often in response to changes in background colour.